The Clinical Core of this Program Project (PP) was established at the time of the first year of funding to recruit patients with Alzheimer's Disease and Parkinson's Disease for clinical assessment and brain tissue donation. Two existing clinical centers were organized to achieve the stated goals and specific aims at the University of Pennsylvania (UP) and the Graduate Hospital (GH). An efficient structure for evaluating patients and requesting consent for autopsy has been created. The aims and methods described later in this section of the application represent a continuation and refinement of the broad goals of the first cycle of the PP. We will continue to recruit well studied patients and to solicit donations of brain tissue. There will be stronger emphasis on the evaluation of the neuropsychological aspects of PD. Whereas in the previous application, we concentrated on conventional clinical assessments of physical and mental features of PD, we have outlined in this application our plans to conduct a longitudinal study of the potential of a particular battery of neuropsychological tests to predict the eventual development of dementia in a cohort of PD patients over 65. Finally, we will correlate a number of clinical features of PD and AD (e.g. the distribution of Apolipoprotein E alleles) with findings at autopsy to define with greater precision criteria for Diffuse Lewy Body Disease (DLBD) and to identify markers of disease progression.